1. Field of the Invention
The present invention relates to a power supply system for a transport vehicle. In particular, the power supply system can be used to supply power to running systems such as life support, controls, compressor, and/or propulsion.
2. Discussion of Background Information
Moving vehicles in transportation systems, e.g., railway or bus systems, can use an onboard power supply for running systems such as controls, compressor, and/or propulsion. The power can come from an energy storage device located in or on the vehicle, such as a battery. However, it can be advantageous to use external sources to avoid the mass of any device or system employed to generate or store energy. Such external sources, however, require a transmission method. In practice, vehicles such as buses and trains have utilized external sources to draw power via electric conduction, e.g., via a catenary system or an electrified rail system.
It has also been sought to transmit power in a manner that eliminates the need for transmission of energy via physical contact. One such transmission system has been achieved through inductive coupling. Such systems require a minimalized distance between the transmitter and receiver for maximum efficiency.
Microwave transmission systems have been used in an attempt to transmit power to unmanned aerial vehicles. However, as these attempts have been in the context of open air transmission, these systems suffer from signal dispersion with distance.
Additionally, vehicles with on-board propulsion capability have been sought. Self-propelled vehicles can add flexibility and robustness to a system. This is particularly true for utility vehicles, such as rescue pods, or any vehicle that may need to move inside the system without being strictly constrained by external propulsion sources. Electromagnetic propulsion, which requires a power supply and on-board energy storage in batteries, results in increased vehicle mass. Three-phase electric motors, including induction motors, can be driven by variable frequency drives (VFDs), which accept incoming electrical power, and then output a three-phase alternating current at whatever frequency is necessary to drive the motor. However, such an on-board VFD will also likely be quite heavy and increase the mass of the vehicle.